In recent years, in a soldering process by a flow soldering tank in printed-circuit board manufacturing, a jig for masking a region other than a region to solder on is frequently used. Since repetitively using such a mask jig (called the dip palette or the carrier palette) causes flux to be accumulated and fixed onto a surface, decreasing an accuracy of the mask, it is necessary to perform cleaning periodically.
In general, as such cleaning is performed by dipping in a solvent, consuming a large amount of solvent, a cost increase is inevitable and a burden on an operator is also quite large.
A known method of spraying the solvent onto the cleaning object in an apparatus without dipping also uses a large amount of solvent.
As a technique for overcoming this problem, a dry type cleaning apparatus is known which cleans a cleaning object by causing a flying cleaning medium to be in contact therewith.
Patent documents 1 and 2 disclose a cleaning method, wherein an opening is provided on a side face of a cylindrically-shaped container, a cleaning medium is caused to fly in a circumferential direction in the container with a revolving air flow formed by a compressed air flow, to cause the cleaning medium to collide with the cleaning object which is in contact with the opening.
However, with this method, the revolving air flow is formed by the compressed gas flow, so that a problem can not be avoided that the cleaning medium leaks out of the container when the cleaning object is separated from the opening.
In order to overcome this problem, in Patent document 1, a net member is provided at the opening to prevent the leakage. However, new problems arise such as energy decreasing when the cleaning medium collides with the cleaning object, and cleaning capabilities decreasing due to the cleaning medium getting caught in the net member.
In Patent document 2, which discloses providing an opening and closing lid which blocks an opening to prevent leakage, it is necessary to perform blocking by quickly moving the opening and closing lid when a cleaning object is separated from the opening, so that there are problems that an operator is compelled to provide unnecessary attention and efforts and that, the mechanism is complex, is difficult to operate, and is susceptible to failures.
In view of the circumstances as described above, the applicant of the present application has proposed a dry type cleaning apparatus, wherein a cleaning medium in a form of thin flakes is caused to fly with a revolving air flow generated by an air flow which flows from outside of a housing to inside thereof via a ventilation path (an inlet) while a suction unit is connected to the housing and an opening is blocked by the cleaning object, and wherein gas and dust are permitted to pass within the housing while not allowing the cleaning medium to pass therethrough (for example, a mesh-shaped porous unit being provided therein causes the cleaning medium to stay in a revolving air flow forming region, causing the cleaning medium to continuously fly and circulate with the revolving air flow (Japanese Patent Application No. 2010-175687 (below called “a prior application technique”))).
According to this dry type cleaning apparatus, even if the cleaning object is separated from the opening, the same level as the atmospheric pressure is reached in the ventilation path, the revolving air flow vanishes, and also a large amount of outer air flows into the housing from the opening due to negative pressure caused by suction, so that the cleaning medium within the housing is suctioned to the porous unit and stays within the housing, causing no leakage from the opening.